Field of the Invention
The present disclosure relates to an electrophotographic image forming apparatus such as a printer, copying machine, facsimile, or multi-function peripheral.
Description of the Related Art
Electrophotographic image forming apparatuses using a so-called intermediate transfer method are known in which full-color toner images are formed on an endless intermediate transfer belt. The intermediate transfer belt is stretched by a plurality of tension rollers such that the intermediate transfer belt is freely rotatable. In this case, so-called “belt deviation”, which is a situation in which the intermediate transfer belt (hereinafter, simply referred to as “belt”) which is rotating is moved to one of the end sides of the rollers, can occur depending on the accuracy of outer diameters of the rollers, the accuracy of relative alignments between the rollers, etc. To correct “belt deviation” and locate the belt in a predetermined position in the width direction (the direction intersecting with the rotation direction of the belt), Japanese Patent Application Laid-Open No. 2014-178505 discusses an image forming apparatus including a steering unit has been discussed. In the image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2014-178505, the steering unit autonomously swings according to the balance of a friction force generated between one of tension rollers called steering rollers and the belt to correct “belt deviation”.
Further, a cleaning unit is provided to the image forming apparatus to remove attached materials, such as toner and paper dust, remaining on the belt after the transfer. The cleaning unit is supported by the steering unit such that the cleaning unit and the steering unit are integrally swingable, as in the apparatus discussed in Japanese Patent Application Laid-Open No. 2014-178505. In this case, the cleaning unit is supported by a support mechanism provided to the apparatus body to reduce the force applied by the gravity to a steering shaft, frame, etc. of the steering unit.
In the cleaning unit, a cleaning blade (hereinafter, simply referred to as “blade”) rubs the belt across the width direction to remove attached materials remaining on the belt, so the blade and the belt are abraded due to use over time, environmental changes, etc. As the abrasion is developed, the friction force between the blade and the belt increases, and this can cause the blade to vibrate. If the blade vibrates, a fixing sheet metal holding the blade across the width direction transmits the vibration of the blade to the body of the cleaning unit (hereinafter, referred to as “unit body”), such as a storage container, and this can cause the unit body to vibrate. If the unit body vibrates, a loud vibration sound is produced, and cleaning defects are likely to occur. Japanese Patent Application Laid-Open No. 2010-20134 discusses an image forming apparatus in which the unit body is brought into contact with an elastic member so that the elastic member reduces vibrations of the unit body.
Meanwhile, in cases in which the fixing sheet metal is supported at both end portions in the width direction by the unit body, the fixing sheet metal is likely to vibrate in proportion to the friction force between the blade and the belt with its central portion in the width direction being more deflected than the end portions are deflected (so-called “natural vibration”). However, the apparatus discussed in Japanese Patent Application Laid-Open No. 2010-20134 becomes unable to reduce vibrations of the unit body if the deflection, i.e., amplitude, of the fixing sheet metal increases. Thus, there have been demands for an apparatus capable of preventing deflections of the fixing sheet metal to reduce vibrations of the unit body, but such an apparatus has not been discussed.